Today the Earth is at aphelion, its farthest distance from the Sun during the whole year, and this year the Earth will be at its second farthest aphelion of the century. Not that it will feel much different though.

The reason for aphelion is the slightly oval-shaped orbit of the Earth around the Sun, with the Sun slightly off-centre. So at this aphelion the Earth lies about 152 million km (94.5 million miles) away from the Sun, roughly 2.4 million km (1.5 million miles) more than average.

That means that the Sun will appear 1.7 per cent smaller in the sky and 7 per cent less bright at aphelion than at perihelion, its closest distance to the Sun, which happened in early January. This makes our summers slightly cooler in the northern hemisphere, but the difference is hardly noticeable.

Another strange effect at aphelion is that the Earth travels most slowly in its yearly orbit – an illustration of this can be seen at www.analemma.com. This slowing down stretches out the summer in the northern hemisphere by almost five days.

The elliptical orbit, as well as the tilt of the Earth, can also add up to 15 minutes’ difference between sundial and clock time. This is called the equation of time.